Directional control and relief valves



Nov. 24, 1964 P. E. REDELMAN ETAL 3,158,167

DIRECTIONAL CONTROL AND RELIEF VALVES Filed Jan. 2, 1962 f2 /50 f CYLINDER OR OTHER D EVICE OIL RESERVOIR 42 26/1 32 4 Q L 1 V /7 m E Q l\ v 7 I" F mm! I I f/ I /4 1 I I "v A! f 2 f 5 4? 57 33 27 20 22 25 6 23 34 It 8 REVERSlNG PUMP INVENTORS.

PAUL E. REDELMAN B GLEN E. CHILDRESS mea J a M/J M/ ATTORNEYS United States Patent 3,158,167 DIRECTIONAL CGNTRUL AND RELIEF VALVES Paui Reriehnan and Glen E. Chiidress, Chicago, ilh, assignors to American Brake hoe Company, New York, N.Y., a corporation of Delaware Filed Jan. 2, 1962, Ser. No. 163,623 4 Claims. (Cl. 137-87) This invention relates to directional control and relief valves, and in particular to a valve of this kind adapted for use in the hydraulic system of a cylinder, or like arrangement.

There are numerous instances of course where it is necessary to reverse the flow of hydraulic fluid. An example occurs in reversing the flow of fluid to a cylinder arranged to throw the points of a railroad switch. Such reversal entails the need for a directional valve which heretofore has commonly taken the form of a four-way valve of rather complicated structure, and it is usually necessary to associate relief valves and pilot valves therewith.

it will be recognized from the foregoing that the directional control of hydraulic fluid can entail complicated valving, and the primary object of the present invention is to include a directional valve and associated relief valving in a common valve mechanism that includes relatively few working parts. Specifically, it is the object of the present invention to construct such a mechanism inclusive of a body or housing, a spring centered slide, a double headed shuttle valve reciprocally related to the slide, and adjustable stops related to the shuttle valve.

Other and further objects of the present invention will be apparent from the following description and claims and are illustrated in the accompanying drawing which, by way of illustration, shows a preferred embodiment of the present invention and the principle thereof and what is now considered to be the best mode contemplated for applying that principle. Other embodiments of the invention embodying the same or equivalent principles may be used and structural changes may be made as desired by those skilled in the art without departing from the present invention and the purview of the appended claims.

In the drawings:

The figure is a sectional view of a valve mechanism constructed under and in accordance with the present invention, and illustrated schematically in association with a reversing pump, an oil reservoir and a cylinder.

The valve mechanism of the present invention is illustrated at 16 in the drawing inclusive of a cylindrical housing 11 having one end wall 12 integrally cast therewith. The opposite end of the housing 11 is closed by a removable end cap 14 secured to the housing by cap screws 15.

Adjustable stops 16 and 17 are threadedly retained at the end walls thus afforded at the opposite ends of the housing 11, and these stops include inwardly projecting extensions 18 and 19 serving a purpose to be described hereinafter.

The interior of the housing 11 is occupied in part by a movable sleeve-like slide 20 having an outer circular wall in sliding contact with the inside diameter or inner wall of the housing 11. A pair of seal rings 22 and 23 are disposed in annular openings in the outer circular wall of the slide 20.

The slide 20 includes an internal bore 25 divided by a guide 26 in the medial portion thereof. The guide 26 is formed with an opening 26A, and the stem 27 of a double headed reciprocal shuttle valve 30 is disposed freely therein. Thus, the shuttle valve 30 includes a pair of flat valve heads 31 and 32 at opposite ends of the stem or shaft 27, adapted to seat in a fluid tight relationship in Patented Nov. 24, 1954 respective seats 33 and 34 formed at the opposite ends of the bore of the slide 20.

The exterior of the slide 20 is formed in the medial portion thereof with an annular passage 38 which communicates with the internal bore 25 through a transverse passage 40 adjacent the guide 26. The passage 38 is adapted to communicate with a drain port 42 in the housing 11, in turn adapted to be connected to an oil reservoir as shown in the drawing. At any angular portion of the slide, the groove or passage 38 is in communication with the port 42.

The slide 29 is held in the position illustrated in the drawing by a pair of centering springs 44 and 45. It will be further noted that the valve heads 31 and 32 are opposite the stops 18 and 19 which themselves are located in respective chambers 48 and 49 within the housing 11 at opposite ends of the slide 20. The springs 44 and 45 are assigned to respective ones of the chambers.

Additionally, it will be observed that either valve head 31 or 32 is adapted, when fully seated, to close off the interior or bore 25 of the slide 20 relative to respective associated chamber 48 or 49. This is chamber 48 in the circumstance illustrated. The shuttle valve is also dimensioned and the valve seats so spaced that under such circumstances the other valve head (31) is displaced from its seat, whereby chamber 49 is in communication with the port 42.

The valve 10 is illustrated in the present instance for purposes of disclosure as adapted to control operation of a cylinder 50 having a piston 52 therein. The piston rod 53 will be connected to a throw rod, machine tool ram or the like that is to be controlled. Thus, hydraulic fluid under pressure is to be directed into one end or the other of the cylinder 50 and the opposite end is to be connected to drain or reservoir.

To this end, the portion of the housing 11 associated with the chamber 48 thereof is provided with a port 55 in turn connected to what corresponds to the rod end of the cylinder 50. In like manner, the portion of the housing 11 corresponding to the chamber 49 is provided with a port 56 connected to what amounts to the piston head end of the cylinder 50.

The valve mechanism 10 of the present invention is specifically adapted to be used with a reversing pump 57, the direction of rotation of which determines the direction of movement of the piston 52. Thus, the pump 57 in efiect has two outlets respectively connected to a port 58 of the housing 11 corresponding to the chamber 48 and a port 59 in the housing 11 corresponding to the chamber 49.

When the pump 57 is operative to pump fluid under pressure, either the valve 31 or the valve 32, depending upon the direction of travel of fluid under pressure, will be seated because of the pressure established in its chamber. This pressure need not be much since the shuttle valve is not biased to any position. Resultantly, fluid under pressure will flow out one of the ports 55 or 56 causing the piston 52 to move in an appropriate direction, and the opposite end of the cylinder will be connected through the open one of the valves 31 or 32 to the oil reservoir. In the event of a block or an excess amount of fluid under pressure, the valve 31-32 assumes a position with seats 33 or 34 closed and thereby becomes a relief valve as will be explained below.

Thus, in the drawing the pump 57 is illustrated as furnishing fluid under pressure to the port 58 of the valve housing 11. This causes the valve 32 to seat tightly in its associated seat 34 in the slide 20. The spring 44 holds the slide 21E against movement, except under excessive pressure build-up as will be noted hereinafter. Spring 45 functions the same way but in an opposite sense.

Resultantly, fluid under pressure is pumped throug chamber 48 of the valve mechanism and out port 55 to the rod end of the cylinder 50, causing the piston 52 to move to the left.

Hydraulic fluid trapped in the cylinder 56 at the head end thereof enters the valve housing 11 through the port 56, and flows through chamber 49 to the port 59 corresponding to the inlet or low pressure side of the hydraulic system. Because of the displacement of the piston rod 53, there will be more hydraulic fluid forced from the cylinder than is entering the cylinder, and this excess will flow through the valve port 33, relative to which the valve 31 is unseated, to the bore 25 in the slide 20 and out port 42 to the oil reservoir or other low pressure sink. If the pump 57 is reversed, a flow reverse to that described above takes place.

In the event that movement of the piston 52 should be prevented at a time when the pump 57 is still operative, there will be a build-up of pressure in the rod side of the cylinder 5t under the circumstance illustrated. If this condition continues, a pressure will eventually be reached where the force on the right-hand end of the slide 26*, having the valve 32 seated, will overcome the centering or return force of the spring 4.

When this condition is reached, the slide 20 and the shuttle valve will move as a unitary body to the left in the housing 11 until the valve head 31 strikes the stop 13, whereupon the valve 32 will be unseated, permitting fluid under pressure in the chamber 48 to drain through the opening disclosed between the valve 32 and its seat 34. As a consequence, the pump 57 will pump directly to the oil reservoir or to its own inlet. When the pressure is released, the spring 44, which was compressed, will return the slide to the position shown.

The reverse situation, with the slide 2 d moving against and compressing the spring 45, until the valve head 32 strikes its stop 19, will be readily apparent.

It will be seen from the foregoing that under the present invention there is afforded a valve mechanism available as a unitary body in which both directional control and relief are afiorded, and this is made possible by using relatively few parts such that the entire assembly can be neatly packaged in a relatively small space.

The shuttle valve is not biased and has no neutral or home position. It rests in the position it last attained. All oil or hydraulic fluid need not be returned to the reservoir, but rather the pump takes what is necessary from either the cylinder or the reservoir, depending upon the stroke of the piston. The pump can of course be located differently from the position shown, as for example between the cylinder and the valve 10.

There need be only a single line communication to the reservoir, and relief valves are not required in this line. It will be recognized that the shuttle makes this valve mechanism self-bleeding.

bers of the housing, a slide disposed in the housing for movement between the stops, said housing having ports in communication with said chambers enabling fluid under pressure to flow into and from said chambers, a unitary shuttle valve supported by said slide and having a valve head at each end thereof opposite a stop and adapted to close on a valve seat at the corresponding'end of the slide when there is fluid under pressure in the chamber associated with the closed valve head, said slide having passage means in communication with said valve seats and in communication with a drain port in said housing adapted to be connected to a reservoir or the like for fiuid at low pressure, said valve heads being so spaced that when one valve head closes as aforesaid the other is displaced from its seat communicating the chamber having the displaced valve with the passage means in the slide that communicates with said drain port, and resilient means for normally holding the slide stationary and being yieldable to pres-sure of a predetermined magnitude acting at one end of the slide having a closed valve head enabling the latter valve and the slide to move together until the displaced valve head strikes its stop, whereupon the closed valve is moved away from its seat to communicate its chamber with the drain port.

2. A directional control and relief valve according to claim 1 wherein the resilient means is in the form of a spring in each chamber.

3. A directional control and relief valve according to claim 2 wherein the slide is a one-piece member having a bore the ends of which present the valve seats, said slide in the medial portion being formed with the passage means that communicate with the drain port, and said springs bearing on the ends of the slide that surround the valve seats.

4. A directional control and relief valve according to claim 3 wherein the stops are adjustable.

References Cited in the file of this patent UNITED STATES PATENTS 2,441,201 Ludwig May 11, 1948 2,590,454 Pilch Mar. 25, 1952 2,716,995 Baugh Sept. 6, 1955 

1. A DIRECTIONAL CONTROL AND RELIEF VALVE COMPRISING A HOUSING HAVING A PAIR OF STOPS LOCATED IN RESPECTIVE CHAMBERS OF THE HOUSING, A SLIDE DISPOSED IN THE HOUSING FOR MOVEMENT BETWEEN THE STOPS, SAID HOUSING HAVING PORTS IN COMMUNICATION WITH SAID CHAMBERS ENABLING FLUID UNDER PRESSURE TO FLOW INTO AND FROM SAID CHAMBERS, A UNITARY SHUTTLE VALVE SUPPORTED BY SAID SLIDE AND HAVING A VALVE HEAD AT EACH END THEREOF OPPOSITE A STOP AND ADAPTED TO CLOSE ON A VALVE SEAT AT THE CORRESPONDING END OF THE SLIDE WHEN THERE IS FLUID UNDER PRESSURE IN THE CHAMBER ASSOCIATED WITH THE CLOSED VALVE HEAD, SAID SLIDE HAVING PASSAGE MEANS IN COMMUNICATION WITH SAID VALVE SEATS AND IN COMMUNICATION WITH A DRAIN PORT IN SAID HOUSING ADAPTED TO BE CONNECTED TO A RESERVOIR OR THE LIKE FOR FLUID AT LOW PRESSURE, SAID VALVE HEADS BEING SO SPACED THAT WHEN ONE VALVE HEAD CLOSES AS AFORESAID THE OTHER IS DISPLACED FROM ITS SEAT COMMUNICATING THE CHAMBER HAVING THE DISPLACED VALVE WITH THE PASSAGE MEANS IN THE SLIDE THAT COMMUNICATES WITH SAID DRAIN PORT, AND RESILIENT MEANS FOR NORMALLY HOLDING THE SLIDE STATIONARY AND BEING YIELDABLE TO PRESSURE OF A PREDETERMINED MAGNITUDE ACTING AT ONE END OF THE SLIDE HAVING A CLOSED VALVE HEAD ENABLING THE LATTER VALVE AND THE SLIDE TO MOVE TOGETHER UNTIL THE DISPLACED VALVE HEAD STRIKES ITS STOP, WHEREUPON THE CLOSED VALVE IS MOVED AWAY FROM ITS SEAT TO COMMUNICATE ITS CHAMBER WITH THE DRAIN PORT. 